The interest in vehicle systems for the transportation of people and things, e.g. goods, along a track has gained importance with the development of urban facilities, shopping centers, transportation centers and the like. It is not uncommon for a shopping center or a transportation facility to be provided with a track system along which a plurality of vehicles, e.g. simple platforms or more complex cars, are displaced between embarkation and disembarkation stations through high-speed regions. Such vehicle systems have been provided between urban centers, between urban centers and suburban parking facilities and even within industrial installations such as a plant where goods or people are to be moved from one place to another.
Such systems generally comprise a multiplicity of vehicles which must be displaced at variable speed, i.e. at a low or zero speed through an embarkation or disembarkation station, and at a relatively high speed between stations.
Several different solutions have been proposed for the operation of such vehicle systems at variable speed. It has been suggested, for example, to pass the vehicle through fixed locations along a road bed or track at which a speed impulse is imparted to the vehicle. This is the case with linear motors or friction drive wheels.
There are also systems in which the vehicle is entrained in stages. In most of these entrainment systems, it is necessary to provide distinct drive devices for the high-speed sector and for the low-speed embarkation and disembarkation sectors, and even a separate drive for the vehicle-recycling sector. The drives at the embarkation/disembarkation sectors and the recycling sector, of course, operate at lower speed than the drive controlling displacement between embarkation and disembarkation sectors.
The passage of a vehicle from one such sector to another or from one drive system to another poses problems with respect to synchronization which has been found to be a highly delicate matter especially since the vehicles must generally be displaced in a relatively tight or closely adjacent formation for reasons of safety.
Systems in which the entire drive is brought to a standstill for each immobilization of the vehicle are disadvantageous because of the inertial problems of starting and stopping, as well as the problem of timing the stopping so that vehicles are not halted when they should be in a high-speed operating mode.
Systems in which a common drive is provided for all of the vehicles which are individually released and recoupled to the drive at the embarkation/disembarkation stations also are not fully satisfactory because the vehicles cannot be maintained in a fixed relationship in such systems and frequently problems are encountered with respect to recoupling of the vehicle to or decoupling it from the drive.